A jaw tracking device is a diagnostic dental instrument used for displaying and/or recording the movement of a patient's lower jaw and mandible. In a typical arrangement, a magnet is temporarily mounted beneath the lower lip of the patient. The jaw tracking device includes an array of magnetic sensors positioned on opposite sides of the patient's mandible. As the patient's mandible moves, the distance between the magnet and each of the sensors varies, and each sensor generates a corresponding electrical signal. The electrical signals from the sensors may be processed to produce data that indicates mandible movement in an anterior/posterior, lateral and/or vertical plane. Selected views of such data may be presented to an operator on the display screen of a monitor or oscilloscope. Typically, a jaw tracking device can also generate a waveform indicative of the vertical velocity of the mandible over time. A jaw tracking device can easily and quickly provide the kind of factual information needed to determine and diagnose an occlusal problem.
Although jaw tracking devices have been used with great success for many years, there are difficulties inherent with the use of magnetic sensors to track mandible movement. To increase accuracy and dynamic range, it is important that the sensors be as sensitive as possible to variations in the magnetic field caused by movement of the magnet with respect to the sensors. Because of the low-level nature of the signals produced by magnetic sensors, it is also important to minimize the effects that other parameters, such as temperature change, may have on the sensor output signals.